“Not surprisingly, the Supreme Court has again rejected the argument that saying the Pledge of your own free will creates an official state religion,” said attorney Eric Rassbach, litigation director at the religious liberty defense group the Becket Fund.

“The words 'one nation under God' make clear the bedrock American principle that our rights come not from the State, but are endowed by our Creator.”

On Monday, the Supreme Court rejected Newdow's appeal from the First Circuit Court of Appeals in Boston. Newdow had attempted to halt the ability of schoolchildren in Hanover, New Hampshire from reciting the Pledge voluntarily.

In March, the Supreme Court also rejected Newdow's appeal from a loss in the Ninth Circuit Court of Appeals in San Francisco.

In both cases, the non-profit Becket Fund for Religious Liberty and global Catholic fraternal organization the Knights of Columbus intervened in the lawsuits to help school children who want to recite the pledge.

The Knights of Columbus led the effort to add the phrase “under God” to the Pledge 55 years ago.

The Becket Fund said in its briefs filed in the First Circuit and the Ninth Circuit that there is a connection between the pledge and other statements like the Declaration of Independence and the Gettysburg Address. The briefs argue that each of those documents express the basic American philosophy that civil rights are inalienable because government does not create them.

Rassbach warned, however, that Newdow's latest attempt to remove the words “under God” may not be the last challenge to the pledge.

“Dr. Newdow has said that he will continue to challenge the pledge around the country, and we will be there to defend it,” he said.